The sintering behavior of ultra-fine Mo–Cu composite powders and the sintering properties of the composite compacts

• The superfine Mo–Cu powders showed remarkable sinterability at solid phase sintering temperature.
• Homogeneous microstructure could have significant contribution to the solid phase densification.
• Liquid copper contributes little to densification of the Mo–Cu compacts, even produces some adverse effects.

Nanocrystalline Mo–25 wt.%Cu composite powders were synthesized by ball-milling, calcinating and subsequent hydrogen reduction process. MoO3 and CuO powders were used as precursors. The sintering behavior of ultra-fine Mo–Cu composite powders and the sintering properties of the composite compacts were investigated. The densification, microstructure, hardness, electrical conductivity, thermal conductivity and coefficient of thermal expansion were tested after solid phase sintering and liquid phase sintering. Relative density near 96% was achieved for the specimen which was compacted under a very low pressure of 32 MPa and sintered at 1050 °C. It reveals that high-energy ball milling increases the contribution of solid phase sintering of Mo and Cu particles on the densification. The microstructure of the sintered compacts observed by scanning electron microscopy showed homogenous dispersion of Mo and Cu phase. The final product showed good physical and mechanical properties.